Electric furnace



May 10, 1932.

A. RUCKSTAHL ELECTRIC FURNACE Filed Oct. 4. 1950 2 Sheets-Sheet l I A TTORNE Y.

May 10, 1932. A. RUCKSTAHL ELECTRIC FURNACE 2 Sheets-Sheet 2 Filed Oct. 4, 1950 INVENTOR. flzf/e'w F r/rs m #4 A TTORNE Y.

Patented May 10, 1932 UNITED STATES PATENT OFFICE ALFRED RUCKSTAHL, or DETROIT, MICHIGAN, ASSIGNOR r HOLCROFT & COMPANY, or nn'rnorr, MICHIGAN, A-coRroRArIoN or mcmean ELECTRIC FURNACE Application filed October 4, 1930. Serial No. 488,840.

This invention relates to electric furnaces of the resistor type, and the object of the invention is to provide a means utilizing a minimum amount of water or other cooling medium for cooling the supports of an electric resistor or element to prevent the supports from melting.

Another object of the invention is to provide a furnace having heating elements consisting of bars of refractory material mounted in water'cooled supports extending into the furnace wall and supporting the refractory bars in the furnace chamber in order to heat the said chamber.

A further object of the invention is to provide awater cooling arrangement whereby the heated water or steam generated in the element support is absorbed or condensed in passing through the cooling water producing a circulation in the support.

further object of the invention is to pro- A vide a devibe arranged to release any pressure generated by heat in the support so that there can be no accumulation of pressure at any point within the device.

-These objects and the several novel features of the invention are hereinafter more fully described and claimed, and the preferred form of construction by which these objects are attained is shown in the accompanying drawings in which Fig. 1 is a transverse section through a furnace embodying my invention.

Fig. 2 is a longitudinal section partly in elevation to show the construction.

The device comprises a frame 1 in which the heat insulating blocks 2 are supported. These blocks are arranged so as to provide a central heating chamber 3. Opening into each side of the heating chamber is a series of tubes 4 which are supported at the inner ends in refractory blocks 5. \Vithin each opening 4 is a tube 6 having a metal head 7 welded thereto and a refractory bar 8 is supported in the recess provided therefor in the head 7. A brass casting 9 is threaded onto the outer end (if-each tube 6 and each casting is provided with a recess 10 therein open to the interior of the tube 6. Each casting 9 is provided with a boss 11 having an electric insulating lug 12 secured thereto which is engaged by an arm 13 pivoted to the boss 14 on the casting 15. Each arm 13, as shown in Fig. 2, is provided a with a notch through which a bolt 16 extends-and this bolt is pro 'vided with a nut thereon and a coiled spring 17 is positioned between the nut and the arm 13. These coiled springs place a pressure on the arms 13 on opposite sides of the furnace'as will be understood from Fig. 1 thus forcing the tubes 6 inwardly and firmly supporting the refractory bars 8 between the alloy heads 7 of the tubes. A tubular member 18 is threaded into each casting 9 and opens into the chamber 10 and asteam hose 19 is secured to the member 18 and extends upwardly and is connected to a pipe20.

This pipe 20 is provided with a shut off valve 21 which is normally in the open position. Each pipe 20 opens into the interior of an elongated tank 22 shown in Figs. 1 and 2 and this tank is provided with an inlet pipe 23 opening into the top of the tank and these inlet pipes 23 are supplied through a water main 24. An overflow pipe 25 is provided in each tank and these overflow pipes are connected together to discharge through the discharge pi e 26 which leads downwardly as shown in L igs. 1 and 2 and discharges into a trough 27 which leads along the side of the furnace and is preferably connected to discharge into the sewer. With this arrangement, as will be understood from Fig. 2., the water flows into one end of the tank through the inlet pipe 23 and flows outwardly through the outlet pipes 25 and 26 at the opposite end of the tank. By this arrangement a constant water level is maintained in the tank at all times. To connect the device in an electric circuit the electric terminals are connected to the bosses 11 on the castings 9 and the current will flow through the supporting tubes 6 and refractory bar 8. This current passing through the refractory bar heats the bar to a high temperature and as there is a multiplicity of these bars mounted in the furnace as will be understood from Fig. 2 the furnace chamber 3 is heated to a high temperature. The articles to be heat treated are inserted into the furnace the steam may very readily escape.

I by fresh cold water from the tanks.

through the slot 28 provided therein, as shown in Fig. 2. 4

The water from the tanks 22 passes through the pipes 20, the steam hose 19, the pipe 18 and into the interior of each tube 6. The heads 7 of these tubes becomes heated by contact with the refractory bar 8 and, as the heat is conductedto the water adjacent these heads 7, a pressure is produced in the tubes 6 and the hot water or steam is forced back into the steam hose 19 and into the tanks 22. By its contact with the cold water the heat is absorbed and flows back into the tube 6 as cold water. This produces a continuous circulation of hot water or steam and cold water through the tubes 6 which cools the heads 7 thereon. Under normal operation some steam is generated but this is condensed in the steam hose 19 or in the tank 22 and the steam or hot water is constantly replacied T 1e water inlet pipe 24.- supplies fresh water to prevent the water in the tanks 22 from boilmg.

It will be noted that there is no pressure on the water from the main and consequeintly t is also to be noted that the steam hose 19 insulates the castings 9 from the arms 13 and frame of the furnace. With this type of furnace where a battery of refractory bars is utilized the fresh cold water in the tanks 22 is constantly flowing into the refractory bar supports to replace the steam generated therein.

From the foregoing description it becomes evident that the device is very simple and efiicient in operation, will not easily get out of order, will efliciently cool the refractory bar supports and provides a device which accomplishes the objects described.

Having thus fully described my invention, its utility and mode of operation, what I claim and desire to secure by Letters Patent of the United States is- 1. In a device' of the character described, an electric furnace having a series of openings in opposite sides thereof a series of hollow tubular refractory bar supports mounted in the said apertures, a series of refractory bars mounted between and supported by the said supports, the refractory bars and supports being adapted for connection in an electric circuit, a tank at each side of the furnace and above the said supports. a water supply pipe opening into' the top of each tank, an outlet pipe one end opening above the bottom of each tank open to atmosphere to prevent pressure in; the tanks, and a series of conduits each connecting the bottom of one of the tanks with each of the refractory bar supports on the respective sides of the furnace, the said conduits being provided with a section of rubber hose, the conduits opening into the interior of the hollow refractory bar supports- 2. In a device of the character described, an electric furnace having a series of openings in opposite sides thereof, a'series of hollow refractory bar supports mounted in the said openings, a series of refractory bars mounted between and supported by the said supports, the refractory bar and supports being adapted for connection in an electric circuit, means for maintaining a tension on the refractory bar supports to support the refractory bars therebetween, a tank mounted above said supports open to atmosphere to prevent pressure therein, means for maintaining a constant water level in the said tank, and a series of conduits each connecting the tank with the interior of one of the refractory I bar supports.

3. In a device of the character described, an electric furnace having a series of open ings in opposite sides thereof, a series of hollow refractory bar supports mounted in the said openings, a series of refractory bars mounted between and supported by the said supports, the bar supports being adapted for connection in an electric circuit. means for maintaining a'tension on the refractory bar supports to hold them in contact with the refractory bar, a tank mounted above the furnace open to atmosphere to prevent pressure therein, and a series of conduitseach connecting the tank with the interior of one of the hollow refractory bar supports.

4. In a device of the character described, an electric furnace having a series of openings in opposite sides thereof, a series of hollow tubular refractory bar supports mounted in the'said apertures, a series of refractory bars mounted between and supported by the said supports, an overhead tank mounted above the furnace, an inlet for the tank, an outlet for the tank one end extending above the bottom thereof the other open to atmosphere to prevent pressure therein, and a series of conduits each connecting the bottom of the tank with the interior of one of the refractory bar supports.

5. In a device of the character described, an electric furnace having openings in opposite sides thereof. a pair of refractory bar supports mounted in the said openings, a refractory bar mounted between and supported by said supports, the refractory bar supports being adapted for connection in an electric circuit, a tank mounted above the said suppogts open to atmosphere to prevent pressure therein, and a conduit leading from the tank to the interior of each refractory bar support.

6. In a device of the character described, an electric furnace having a series of openings in opposite sides thereof, a series of hollow refractory bar supports mounted in the said nesaoea oi) ports, a tank mounted above the furnace, an outlet for the tank one end opening above the bottom thereof the other open to atmosphere to prevent pressure therein, and a series of flexible conduits one connecting the tank with the interior of each of the refractory bar supports. h I

7. In a. device of the character described,

an electric furnace having a series of open ings in opposite sides thereof, a series of hollow tubular refractory har supports mounted in the said openings, a series of refractory bars mounted between and supported by the said supports, an overhead tank mounted above the furnace, an iniet for the tank an outlet therefor open to atmosphere to prevent pressure in the tank, means for maintaining a constant Water level in the tank, and a series of conduits one connecting the bottom of the tank with the interior. of one of the refractory bar supports,

8. In a device of the character described, an electric furnace, a series of hollow heating element supports mounted in the "wall of the furnace and adapted to support heating elements therebetween, a tank mounted above the supports and arranged to maintain a predetermined Water level therein open to atmosphere to prevent pressure in the tank, and

conduits each connecting the tank with the interior of one of the heating element supports. I

In testimony whereof I sign this specification.

ALFRED RUCKSTAEL, 

